A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile

A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile Toilets

G. BONIFAZI, R. GASBARRONE, R. PALMIERI, G. CAPOBIANCO, S. SERRANTI

Departments of Medical Sciences and Biotechnologies and of Chemical Eng. Materials, Environment- Sapienza University of Rome,

Abstract

The EU wastewater management industry is continuously looking for innovative technological solutions that can enter the market with a reduced environmental impact. This paper focuses on the problems associated to the disposal of and on the specific market of the so-called mobile toilets. These are independent portable units equipped with sanitary tools that use chemical agents to disinfect the vessel and not connected to the sewer network. With growing awareness towards effective , mobile toilets have gained immense popularity in recent years and are now widely used at construction sites, event venues, public places, and in several other application like temporary refugee housing, migrants’ camps, military missions, cases of natural disasters, airplanes, trains, campers, caravans and campsites. This paper illustrates a new process for the disposal of organic waste from mobile toilets.

Keywords: Waste Water Treatment Plants, Chemical Portable Toilets, Use of in agriculture.

1. Introduction into surface and ground water and to avoid toxic effects on soil, plants, animals and humans. In The use of in agriculture within the EU is most cases, national authorities have currently regulated only by the limits of heavy implemented policies supporting the use of (Cd, Cu, Hg, Ni, Pb and Zn) listed in sludge in agriculture, as it is considered to be the Council Directive 86/278/EEC. This document best economic and environmental option to deal is now more than 30 years old and most of the with the increasing quantities of sludge EU countries have introduced more stringent produced. In this context, national authorities requirements and have adopted limits for are seeking to increase confidence in the quality concentrations of other , synthetic and safety of products cultivated on sludge organic compounds and microbial fertilised soils. In the context of uncertainties contamination. There is a need to update these concerning the potential impacts on human regulations taking into account the current risks health and the environment of the various associated with the application of sludge to disposal and recycling routes, all main agricultural land. In general, sludge is stakeholders are calling for additional characterized by considerable variability in demonstration activities in order to increase nutrient content depending on the wastewater confidence in the use of sludge in source and treatment process. Although agriculture. The development of agricultural nutrients are essential for plant growth, when recycling depends largely on the possibilities to applied excessively (especially nitrogen and improve the quality of the sludge itself and ) they may accumulate in soil and increase confidence in sludge quality. This can be leached and transported by drainage implies the prevention of pollution of the waste systems (particularly nitrogen) or can be water at source and improving sludge treatment transported by water erosion (phosphorus bound as as ensuring the monitoring of sludge to soil particles) and pose a risk to surface water quality. This paper focuses on an innovative and ground water. It is then necessary to have process for the treatment of a particular category the correct safety measures facilitating the of organic residues deriving from the use of prevention of possible leakage of contaminants chemical toilets and from agri-food industry’s production process. 1 International Symposium on Technologies for Smart City – 11th-12th November 2019, Malaga, Spain A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile Toilets

2. Innovative solutions for the market portable toilets to be provided, the locations and the cleaning and disposal intervals. Cleaning The EU wastewater management industry is with collection of waste is the activity that must continuously looking for innovative ensure the hygiene of mobile toilets in service: it technological solutions that can enter the market consists in emptying the waste collection tank, with a reduced environmental impact. This cleaning it, restoring sanitizing liquids and paper focuses on the problems associated to the consumables, and in the sanitation and disposal of human waste and on the specific disinfection of the . Emptying the market of the so-called mobile toilets (See wastewater collection tank and its relative Figure 1). cleaning are carried out by loading or sucking the resulting waste into tanks mounted on specially equipped vehicles, for subsequent transport to an authorized Plant (WWTP) within the times and in the manner established by the regulations (Figure 2)..

Figure 1: Portable chemical toilets.

These are independent portable units equipped with sanitary tools that use chemical agents to disinfect the vessel, not connected to the sewer network and intended for the use of a single Figure 2: Traditional disposal of sludge from person and temporarily placed in places where a mobile toilets. number of people have to use them in the absence or insufficiency of fixed sanitation The mobile toilets are in general managed or facilities. With growing awareness towards owned by the same company who carries out the effective sanitation, mobile toilets have gained maintenance cleaning, who makes a specific immense popularity in recent years and are now service available to the applicant (public or widely used at construction sites, event venues, private) dealing with efficiency and hygiene. public places, and in several other application From the maintenance cleaning of a portable like temporary refugee housing, migrants’ toilet, modest quantities of waste result (tens of camps, military missions, cases of natural kilos or litres). The waste deriving from the disasters, airplanes, trains, campers, caravans cleaning of the toilets have the same and campsites. These toilets are also called characteristics as those deriving from the “chemical toilets” because the relative waste cleaning of septic tanks: in all there are collection tanks are usually treated with anti- chemicals, residues of cosmetics, fermentation and disintegrating chemical agents detergents, various types of sanitizers in addition with caustic and disinfectant action, which are to waste from human metabolism. This is why, then part of the waste deriving from as such, sludge from chemical toilets cannot be maintenance cleaning and emptying of the tanks normally reused for other purposes and they are themselves. There has been increasing scrutiny commonly sent to WWTP with significant costs over the polluting chemicals currently used in and environmental consequences. The toilets mobile toilets because they are carcinogenic and must be periodically emptied with disposal harmful to the environment and to human health. intervals that depend on the specific application. UNI EN 16194 is the standard specifying the On average, each chemical toilet is completely requirements for services related to the emptied of its content once a week, and every installation of the toilets and those relevant to time a toilet is emptied, about 25 litres of waste chemicals and sanitary products, taking into are collected to be transported to the WWTP. account factors such as hygiene, health and Every time the toilet is emptied it must be safety, cleaning measures, the number of cleaned and sanitized and its tank must be 2 International Symposium on Technologies for Smart City – 11th-12th November 2019, Malaga, Spain A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile Toilets

refilled with clean water along with chemicals. may accumulate in soil and can be leached and On average, the tank is filled with 10 litres of transported by drainage systems or can be water and 1 litre of chemicals. Considering that transported by water erosion and pose a risk to nowadays in Europe there are about 2 million surface water and ground water. It is then chemical toilets in circulation, it can be necessary to have the correct safety measures estimated that every week 2 million litres of facilitating the prevention of possible leakage of chemicals are used to fill the cleaned tanks. contaminants into surface and ground water and When the toiles are emptied, this weekly huge to avoid toxic effects on soil, plants, animals and amount of chemicals will converge in the humans. Since 1986, land application of WWTPs together with the organic materials sludge within the EU has been governed by collected. The environmental problem addressed Council Directive No. 86/278/EEC. It prescribes is characterized by the current need to dispose prior testing of sludge and soil, application of the wastewater in the treatment plant and by the sewage sludge exceeding critical concentrations consequent environmental impact due to the of pollutants to agricultural soil is prohibited, presence of reactive and polluting chemical and soils exceeding permissible concentrations substances. Wastewater in fact, even after cannot receive sewage sludge. This Directive treatment, can end up in areas deemed sensitive has been implemented into the national to the environment and health, or affect larger legislation of member states, most of which have populations. These wastewaters, together with set lower limits than that prescribed in the those produced by septic tanks (and also by the Directive, in order to protect soils and reduce food industry), are a significant source of possible emissions. There is a clear need to pollution that can negatively affect the quality of update these regulations because in many cases, drinking and bathing water. Furthermore, national authorities have implemented policies wastewater can to an aggravation of supporting the use of sludge in agriculture, as it biodiversity reduction and hamper the is considered to be the best economic option to achievement of the objectives set by the Water deal with the increasing quantities of sludge Framework Directive. produced. In the Northern EU countries, less than half of sewage sludge is utilised in 3. Use of sewage sludges in agriculture agriculture, as well as in China, in Japan, in An important issue is the possibility of using Korea, but also in some countries of Africa and sewage sludge in agriculture. In general, sewage South-America. In this context, national sludge is characterized by considerable authorities are seeking to increase confidence in variability in nutrient content depending on the the quality and safety of products cultivated on wastewater source and treatment process. It can sludge fertilised soils. In the context of be suitable for complementing mineral uncertainties concerning the potential impacts fertilisation when used according to the rules on human health and the environment of the and regulations on agriculture. Negative various disposal and recycling routes, all main attitudes and concern about environmental and stakeholders are calling for additional health caused by sewage sludge have demonstration activities in order to increase decreased the spreading of sludge on fields. The confidence in the use of sludge in agriculture. heavy content of sewage sludge has been The Italian Association of Waste Management considered the most significant restricting factor and Remediation of Contaminated Sites ATIA in the agricultural use of sludge. The problem is ISWA considers essential to issue a new clear that heavy metals remain in the soil and many of and organic discipline, especially in relation to them undergo biomagnifications in the food the origin and codes of the sludge that may be chain. Among the heavy metals in sewage admissible to the different forms of recovery, sludge, the most hazardous ones to humans are respecting the constraints imposed by the , , and lead, while , , Community directives on waste (2008/98/EC ) , and in high concentrations are and the protection of the soil in case of use of particularly poisonous to plants. Wastewater can sewage sludge in agriculture (Directive 86/278), also contain several kinds of pathogens, fully supporting the legislative review initiative including microbes, fungi, viruses, protozoa, undertaken by the Italian Ministry of and parasites. Although nutrients are essential Environment. The development of agricultural for plant growth, when applied excessively they recycling depends largely on the possibilities to 3 International Symposium on Technologies for Smart City – 11th-12th November 2019, Malaga, Spain A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile Toilets

improve the quality of the sludge itself and • Primary tank for collecting wastewater. The increase confidence in sludge quality. This semiliquid organic material collected from implies the prevention of pollution of the waste the chemical toilets is discharged into this water at source and improving sludge treatment tank by gravity or using a pump directly as well as ensuring the monitoring of sludge from the vehicles. The tank has a lifting quality. Following the principles of the pump. sustainable development, recirculation of • Roto-sieve drum screens: the material nutrients of human beings from urban areas to undergoes a process thanks to roto- agricultural land represent then one big sieve drum screens, which separate solid challenge. particles and fibres from liquids by screening. 4. The innovative prototype • Secondary tank. In this tank the material An innovative process for the treatment of passes through a grid for further organic residues deriving from the use of homogenization. chemical toilets, from septic tanks and also from • Tank for stabilization. This tank is equipped agri-food industry’s production process has been with a mixing blade and a helix shaped developed. The process represents the natural thickener that shreds the particles. evolution of research activities on the use of a • Oxidation tank: in this tank the separation new biological substance named EIS that allows between the organic substance and the water to fully recover water and organic materials from takes place. sewage to use them in agriculture and avoiding to • Water tank. introduce chemicals in the environment. The • Tank for the EIS. ultimate goal is a 100% valorisation of sewage • Pumps. from chemical toilets transforming it into water • Oxygen meter, probe and sensors. and high-quality according to a circular • Filtration tank with quartzite and activated economy approach. A first small-scale prototype carbon. has been designed, built and validated. The plant is able to produce, without any substantial alteration of the constituent collected substances, three different products.

These are: • Product 1: solid fertilizer resulting from the oxidative production of the natural organic mix made of fluid and particulate solids deposited in the toilets. Such a product is biologically activated utilizing enzymes deriving from the flora and fauna specifically and exclusively present in the waste products resulting from food processing plants, thus substantially contributing to their reuse and valorisation.

• Product 2: recovered water for fertirrigation, characterized by level of BOD and COD almost equal to zero. The recovered water being rich of nitrogenous substances can be re-utilized in crops.

• Product 3: liquid concentrated fertilizer for hydroponics application.

The system is shown in Fig. 3 and consists of Figure 3: System prototype. the following main components: 4 International Symposium on Technologies for Smart City – 11th-12th November 2019, Malaga, Spain A Novel Waste Water Treatment Plant for The Disposal of Organic Waste from Mobile Toilets

results are shown in Table I. 5. Experimental results The plant has been validated in laboratory to produce fertilizer that has been used on a small experimental farm situated close the plant. The technology focus on an aerobic technique allowing to produce quality materials resulting from the oxidative production of the natural organic mix coming from the organic liquids and particulates deposited in the chemical toilets. The process is based on a new organic blend called EIS, consisting exclusively of mix of substances of natural biological origin (i.e. glycerine, ethyl alcohol, natural soap, natural fragrant sanitizer and others) that has been developed by BEB. Several tests, simulations and technical comparisons were made to analyse the possibility to replace chemicals normally used in chemical toilets with EIS. Several analyses have already been conducted on the recovered waste water in order to ensure the compliance with the national laws. The main chemical parameters are reported as follow: Figure 4: Pipeline for fertirrigation.

• mg / L = 5 • BOD5 mg O2 / L = 15 • COD mg O2 / L = 80 • Total phosphorus mg P / L = 1 • Total nitrogen mg N / L = 15 • Absence of coarse materials, heavy metals, escherichia coli and Salmonella Table I: Main results The plant allows to transform the waste into a 6. Conclusions completely organic and aerobically mineralized The developed prototype allows to treat 10m3 of sludge that, after being pressed and dried, will be wastewater/day and transforming around 2,600 made solid and free of humidity. The solid m3/year of sludges in recovered water for fraction is stabilized in the aerobic phase until fertirrigation and in 10,400 kg/year of solid complete mineral oxidation of the organic fertilizer. The proposed solution represents a residue without any harmful emissions. The novelty in the field of the treatment of organic liquid fraction, as well as the solid fraction, will waste. Future experiments will be based on is completely free of pollutants and rich in hyperspectral procedures to monitor the different potassium salts, nitrates and carbonates and has cultivations, to verify the productivity and quality been used as nourishing water for horticultural of the products as well as the composition of soils and fruit crops or for . The fertilizer variation in respect of nutrients contribution. produced by the prototype has been used on an

experimental farm cultivated with salad, 7. REFERENCES valerian, chard and horticultural crops.

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